Conventional automotive disc brake systems comprise a hermetically sealed system employing a fluid for transmission of braking forces exerted by the vehicle operator on the brake pedal to the rotating wheels of the vehicle. Such systems generally include a master cylinder having a fluid reservoir and a piston responsive to actuation of the brake pedal, which causes the fluid to be forced through a distribution system running to each of the wheels. This pressurized fluid actuates another piston at each of the wheels, causing the brake shoes or pads to engage a rotating disc secured to each wheel.
In these disc brake systems, the fluid actuated pistons located at the individual wheels are housed in a caliper which also holds and restrains the brake pads thereby providing the braking force. As these forces are substantial, the housing must necessarily be a massive structure. Further, in that it is necessary to allow the brake pads to move axially with the piston while restraining both radial and circumferential movement of the brake pads, the pad supporting structure of the caliper must be accurately constructed. Also, the brake caliper will have provided in it a fluid chamber and fluid passageways communicating with a bleeder valve, the fluid chamber and provisions for external connection of a brake line. For these reasons, the caliper of a disc brake is necessarily an expensive component of the brake system when compared to the wheel cylinders of the older conventional brake systems, and, thus, it becomes highly desirable to avoid replacement of this component whenever possible.
It is extremely important to the operating efficiency of all fluid actuated braking systems to insure against the presence ao any air being trapped within the system. As air is a compressible gas, the presence of air in any portion of the fluid system will absorb, rather than transmit, the pressure created by the master cylinder. Accordingly, bleeder valves are provided on the calipers which communicate with the fluid passageways to allow air to be expelled from the system. These bleeder valves are normally threaded into an aperture in the caliper housing and have a valve body which engages an accurately machined valve seat contained within the caliper. Occasionally, the threaded bleeder valve aperture may become damaged due to corrosion, lack of necessary care, or the like. Accordingly, the present invention provides a method and device by which this aperture may be repaired with a minimum of effort and expense, thus eliminating the necessity of replacing the caliper itself, as well as the associated expense and delay of repair in attempting to obtain a replacement caliper housing.
Other features and advantages of the present invention will become apparent from a review of the following detailed description of the preferred embodiment in which reference is made to the following drawings.